CCD Bus

The Chrysler Collision Detection multiplex system (CCD bus) consists of a twisted pair of wires. These wires run from one module to another. They receive and deliver coded information between the modules. The information is coded to identify the message as well as the importance of the message. When there are multiple messages trying to access the CCD bus at one time, the code is used to determine which one has higher priority and is allowed to access the bus first.

The two wires (D1) and (D2) of the twisted pair that makes up the CCD multiplex system are called "bus+" (bus plus) and "bus-" (bus minus). Both wires have a measurable voltage level of roughly 2.5 volts. In order to maintain the 2.5 volts on each line and provide a means of transportation for the coded messages, there is a "voltage divider network." This network consists of some modules with bias and some with termination. Bias is the part of the voltage divider network that places both bus+ and bus- at 2.5 volts. Termination is the circuitry required to complete the voltage divider network and also provide some electromagnetic protection for the bus.

NOTE: Communication over the bus is essential to the proper operation of the vehicle's on-board diagnostic systems and the DRBII. Problems with the operation of the bus or DRBII must be corrected before proceeding with diagnostic testing. If there is a problem, refer to Information Bus for diagnosis and repair procedures.